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Tim's Auto Repair, mechanic
Category: Chevy
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Experience:  Have owned a repair shop for 25 yrs.
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1998 Chevy k2500 w/454. problem started 2 weeks ago - died

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1998 Chevy k2500 w/454. problem started 2 weeks ago - died while driving and could not restart. Found a blown ECM fuse (20amp). replaced fuse and fuel pump relay, worked for 3 start and stops with 30 miles in between then same problem. replaced fuel pump and fuel filter. started and stopped 4 times with 50 miles in between but just died again on us. So in the last 3 weeks we've replaced the fuel pump, fuel filter, fuel pump relay and the 20amp fuses. We don't know where to turn next.


if it is dieing after the engine gets hot,and restarts after it cools for a while..the problem may be the crank sensor


Description and Operation


The Crankshaft Position (CKP) Sensor is located in the front engine cover and is perpendicular to the crankshaft target wheel. The air gap between the sensor and the wheel is preset and not adjustable. The target wheel has three slots 60°apart and is keyed to the crankshaft. As the target wheel rotates, the slots passing by the sensor create a change in the magnetic field of the sensor which results in an induced voltage pulse. One revolution of the crankshaft results in three pulses (3x signal). Based on these pulses, the VCM is able to determine crankshaft position and engine speed. The VCM then activates the fuel injector and provides a spark to the Distributor. The relation between the crankshaft position sensor and the target wheel is crucial. The sensor must be exactly perpendicular to the target wheel with the correct air gap.

The crankshaft position sensor provides the VCM with crankshaft speed and crankshaft position. The VCM utilizes this information to determine if an engine Misfire is present. The VCM monitors the Crankshaft Position Sensor (CKP) sensor for momentarily drop in crankshaft speed to determine if a misfire is occurring. When the VCM detects a misfire, a Diagnostic Trouble Code (DTC) P0300 will set. The VCM also monitors the CKP sensor signal circuit for malfunctions. The VCM monitors CKP signal and the High and Low resolution signals. The VCM calculates these signals to determine a ratio. When the VCM detects that the ratio is out of normal operating range, the VCM will set a Diagnostic Trouble Code (DTC) P0337 or a DTC P0338.
Crankshaft Position Sensor Replacement


IMPORTANT: The CKP System System Variation Learning Procedure will need to be performed whenever the Crankshaft Position (CKP) sensor is removed or replaced. Refer to CKP System Variation Learn Procedure.



  1. Remove the electrical connector.
  2. Remove the sensor hold down bolt.
  3. Remove the sensor from the timing cover. NOTE : When installing or removing a crankshaft position (CKP) sensor make sure the sensor is fully seated and held stationary in the front cover before torquing the hold down bolt into the front cover. A sensor which is not seated may result in erratic operation and lead to the setting of false codes.
  4. Inspect the sensor O-ring for wear, cracks or leakage. Replace if necessary. Lube the new O-ring with clean engine oil before installing.


NOTE : Make certain that the Crankshaft Position (CKP) sensor mounting surfaces are clean and free of burrs before installing the CKP sensor.

  1. Install the sensor into the timing cover.
  2. Install the sensor hold down bolt. Tighten
    • Tighten the hold down bolt to 8 Nm (71 lb. in.) .
  1. Install the electrical connector.
  2. Perform the CKP System Variation Learn Procedure. Refer to CKP System Variation Learn Procedure.
Crankshaft Position System Variation Learn Procedure


  1. Install the scan tool.
  2. Apply the vehicle's parking brake.
  3. Block the drive wheels.
  4. Close the hood.
  5. Place the vehicle's transmission in Park (AT) or Neutral (MT).
  6. Idle the engine until the coolant temperature reaches 65°C (150°F).
  7. Turn OFF all the accessories. IMPORTANT: If the Crankshaft Position (CKP) System Variation Learn Procedure cannot be completed successfully, refer to DTC P1336 CKP System Variation Not Learned for additional diagnostic information.
  8. Enable the Crankshaft Position System Variation Learn Procedure with the scan tool. IMPORTANT: After the ignition switch is turned to the CRANK position, the Vehicle Control Module (VCM) must see a change in the state of brake switch (Released to Applied) to run the learn procedure. Also, the service brakes and the parking brake must be held throughout the duration of the learn procedure.
  9. Apply and hold the service brakes. IMPORTANT: While the learn procedure is in progress, release the throttle immediately when the engine starts to decelerate. The engine control is returned to the operator and the engine will respond to throttle position after the learn procedure is complete.
  10. Slowly raise the engine speed to 4,000 RPM.
  11. Immediately release the throttle when the engine speed decreases.
  12. Turn OFF the ignition for 15 seconds after the learn procedure is completed successfully.
Customer: replied 7 years ago.
No, it will not start cold and would not start cold any of the previous times. The first time we tried hot and cold (resting 3 days) and would not start until the fuel pump relay was replaced. The second time it happened it would not start hot or cold (resting 2 days) and only restarted after we replaced the fuel pump.


evem though you have a new fuel pump,check the prsure,it can not have less then 58psi at any time,,it is very common to get a bad new pump,,,sometimes you will go through 2 or 3 before you get a good one


Tim's Auto Repair, mechanic
Category: Chevy
Satisfied Customers: 15369
Experience: Have owned a repair shop for 25 yrs.
Tim's Auto Repair and 6 other Chevy Specialists are ready to help you
Customer: replied 7 years ago.
there's pressure in the line (squirts when you depress the valve in the fuel rail) but we can't get it to run in order to check the pressure while the vehicle is running. The fuel pump does pump when you turn the key on and off and the fuse doesn't blow until we try to start (turn key to crank position). And actually it will fire once (don't know on how many cylinders) but after that the fuse is blown and no more spark so it won't start.


i will opt out and let another one of our guys pick this up,,they may have seen this before


Customer: replied 7 years ago.
thanks for trying...
Is the condition with the ECM 1 fuse or the ECM B fuse? There have been issues with the wiring harness at the transmission bellhousing bolts being rubbed through and blowing fuse.
Customer: replied 7 years ago.
ecm b fuse

The oil pressure sender is also powered by this fuse. Disconnect the sensor and check the wires for possible short to ground and verify the connector isn't conaminated with oil. With sensor disconnected, see if the fuse blows when vehicle is cranking. Also check the wiring harness I mentioned before for grounding out at the transmission bellhousing bolts.